JP2009091542A - Method for producing cellulose mixed acylate and new cellulose mixed acylate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for industrially efficiently producing cellulose mixed acylate excellent in various characteristics, particularly optical characteristics. <P>SOLUTION: In the method for producing cellulose mixed acylate, a plurality of acyl groups different in reactivity is introduced into cellulose acetate having a total substitution degree of acetyl groups of 1.5-2.9, for producing cellulose mixed acylate having a total substitution degree of acyl groups of 2.7-3.0. For example, the cellulose acetate as a starting material is reacted with a mixed acid anhydride of a first carboxylic acid corresponding to an acyl group having relatively high reactivity and a second carboxylic acid corresponding to an acyl group having relatively low reactivity, and an acid anhydride or acid halide derivative of the second carboxylic acid to preferentially introduce the acyl group having relatively high reactivity into the 6-position of a glucose skeleton. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a cellulose mixed acylate having a high total acyl group substitution useful as a raw material such as an adsorbent, a film and an optical isomer separating agent, particularly a photographic material and an optical material, and a novel cellulose mixed acylate.

  A cellulose mixed acylate in which a plurality of acyl groups (for example, an acetyl group and an acyl group other than an acetyl group) is introduced into the hydroxyl group of cellulose is known. For example, Japanese Unexamined Patent Application Publication No. 2002-322201 discloses a cellulose mixed acid ester compound in which a hydrogen atom of a hydroxyl group of cellulose is substituted with a substituted or unsubstituted aromatic acyl group and a substituted or unsubstituted aliphatic acyl group. It is disclosed that according to this cellulose mixed acid ester compound, a film excellent in optical isotropy, transparency, water resistance, and dimensional stability can be formed. In the examples of this document, cellulose benzoate trifluoroacetate and the like are synthesized.

Japanese Patent Application Laid-Open No. 2006-328298 discloses an optical film formed by melting a composition mainly composed of cellulose ester, wherein the cellulose ester satisfies the following formulas (1) and (2). Is disclosed.
Formula (1) 2.4 <= X + Y <= 2.9
Formula (2) 0.3 <= Y <= 1.5
(Wherein X represents the degree of substitution with acetic acid and Y represents the degree of substitution with aromatic carboxylic acid)
In the examples of this document, cellulose is used as a raw material, and two kinds of carboxylic acids are reacted with this to synthesize cellulose mixed acylate such as cellulose acetate benzoate. However, this reaction is a reaction under heterogeneous conditions, and the reaction does not proceed uniformly. In addition, it is considered that the more reactive carboxylic acid reacts on the cellulose surface, and then the less reactive carboxylic acid reacts. Furthermore, the cellulose ester derivative to be produced is a composition having a large variation between molecules, such as a derivative rich in acetyl group or a derivative rich in benzoyl group. As a result, the solubility in the solvent differs among the products, causing phase separation or turbidity when used as a dope, difficult to filter, unable to filter, and increasing intermolecular substitution degree distribution. A composition having is obtained.

  Japanese Patent Application Laid-Open Nos. 2007-199392 and 2007-199391 disclose cellulose acylate films having specific optical characteristics. However, in these documents, only those having a high degree of benzoyl group substitution at the 6-position of the glucose skeleton are obtained, and those in which a benzoyl group is selectively introduced at the 2- and 3-positions are not obtained.

JP 2002-322201 A JP 2006-328298 A JP 2007-199392 A JP 2007-199391 A

  In the case of cellulose mixed acylate in which a plurality of acyl groups are introduced into the hydroxyl group of cellulose, the physical properties, particularly optical characteristics, can vary greatly depending on the type, substitution degree, substitution degree distribution, etc. of each acyl group. Therefore, it can be used for various useful applications by adjusting them.

  Accordingly, an object of the present invention is to provide a method for industrially and efficiently producing a cellulose mixed acylate excellent in various properties, particularly optical properties. Another object of the present invention is to provide a novel cellulose mixed acylate excellent in various properties, particularly optical properties.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have responded to (i) a relatively highly reactive acyl group for cellulose acetate having a total acetyl group substitution degree of 1.5 to 2.9. A mixed acid anhydride of the first carboxylic acid and the second carboxylic acid corresponding to the acyl group having relatively low reactivity is reacted with the acid anhydride or acid halide derivative of the second carboxylic acid. Or (ii) reacting a first carboxylic acid corresponding to an acyl group having a relatively high reactivity with an acid halide derivative of a second carboxylic acid corresponding to an acyl group having a relatively low reactivity. Or (iii) without reacting the acid anhydride or acid halide derivative of the first carboxylic acid corresponding to the acyl group having a relatively high reactivity, and then performing a quench treatment or a reaction product isolation treatment An acyl group with relatively low reactivity When the corresponding acid anhydride or acid halide derivative of the second carboxylic acid is reacted, the cellulose mixed acylate having a high acyl group total substitution degree and a acetyl group total substitution degree of 1.5 to 2.9, An acyl group corresponding to the first carboxylic acid is selectively introduced into the 6-position of the glucopyranose skeleton, and an acyl group corresponding to the second carboxylic acid is selectively introduced into the 2nd and 3rd positions of the glucopyranose skeleton. Thus, the present invention has been completed by finding that the cellulose mixed acylate is efficiently obtained and that such cellulose mixed acylate is excellent in optical properties.

  That is, in the present invention, a plurality of acyl groups having different reactivities are introduced into cellulose acetate having an acetyl group total substitution degree of 1.5 to 2.9 so that the acyl group total substitution degree is 2.7 to 3. A method for producing a cellulose mixed acylate of 0, wherein the raw material cellulose acetate is converted into (i) an acyl group having a relatively low reactivity with the first carboxylic acid corresponding to the acyl group having a relatively high reactivity. The mixed acid anhydride with the corresponding second carboxylic acid is reacted with the acid anhydride or acid halide derivative of the second carboxylic acid, or (ii) corresponds to an acyl group having a relatively high reactivity. Reacting a first carboxylic acid with an acid halide derivative of a second carboxylic acid corresponding to an acyl group having relatively low reactivity, or (iii) corresponding to an acyl group having relatively high reactivity No acid of the first carboxylic acid After reacting the product or acid halide derivative, the acid anhydride or acid halide of the second carboxylic acid corresponding to the acyl group having relatively low reactivity without performing quenching treatment or reaction product isolation treatment There is provided a method for producing a cellulose mixed acylate characterized by reacting a derivative and preferentially introducing the acyl group having relatively high reactivity into the 6-position of a glucose skeleton.

  In this production method, it is preferable that the first carboxylic acid is a saturated aliphatic carboxylic acid and the second carboxylic acid is an aromatic carboxylic acid. As the first carboxylic acid, for example, a saturated aliphatic carboxylic acid having 2 to 4 carbon atoms is preferable.

  In (i), a mixed acid anhydride of the first carboxylic acid and the second carboxylic acid is added to the raw material cellulose acetate in an amount of 0.95 to 1.2 with respect to 1 mol of the hydroxyl group at the 6-position of the raw material cellulose acetate. Mole may be reacted with an acid anhydride or acid halide derivative of the second carboxylic acid.

  In (ii), 0.95 to 1.2 mol of the first carboxylic acid is added to the raw material cellulose acetate with respect to 1 mol of the hydroxyl group at the 6-position of the raw material cellulose acetate, and the acid halide derivative of the second carboxylic acid May be reacted.

  Further, in the former stage of (iii), 0.48 to 0.6 mol of an acid anhydride derivative of the first carboxylic acid is added to the raw material cellulose acetate with respect to 1 mol of the hydroxyl group at the 6-position of the raw material cellulose acetate. After reacting or reacting 0.95 to 1.2 mol of the acid halide derivative of the first carboxylic acid with respect to 1 mol of the hydroxyl group at the 6-position of the raw material cellulose acetate, quenching treatment or reaction generation The acid anhydride or acid halide derivative of the second carboxylic acid may be reacted in the subsequent stage without performing isolation of the product.

  In the present invention, the total substitution degree of acyl groups is 2.7 to 3.0, the total substitution degree of acetyl groups is 1.5 to 2.9, and the total substitution degree of acyl groups that are less reactive than acetyl groups is 0. The sum of the degree of acyl group substitution that is less than the acetyl group at the 2-position and the degree of acyl group substitution that is less reactive than the acetyl group at the 3-position is the acetyl group at the 6-position. Greater than twice the degree of acyl group substitution that is less reactive (provided that the acyl groups that are less reactive than the acetyl groups at the 2nd, 3rd and 6th positions are all aliphatic acyl groups) Acyl group substitution, which is less reactive than the acetyl group at the 2-position and acyl group substitution degree, which is less reactive than the acetyl group at the 3-position, is less reactive than the acetyl group at the 6-position. Greater than 1.3 times the degree) To provide a cellulose mixed acylate.

  In this cellulose mixed acylate, the acyl group having a lower reactivity than the acetyl group may be an aromatic acyl group. The sulfate radical content is preferably 200 ppm by weight or less based on the cellulose mixed acylate.

In addition, the total substitution degree of each acyl group of the cellulose acetate used as a raw material and the cellulose mixed acylate as a product can be measured by a conventional method such as ¹ H-NMR method or ¹³ C-NMR method. The substitution degree distribution of each acyl group (substitution degree at the 2nd, 3rd and 6th positions of the glucose skeleton) can be measured by a known method such as ¹³ C-NMR method. Regarding the measurement method, the method of Tezuka (Tezuka, Carbohydr. Res., 273, 83 (1995)) and JP-A-2002-338601 can be referred to.

  According to the production method of the present invention, since cellulose acetate that is easily dissolved in an organic solvent having an acetyl group total substitution degree of 1.5 to 2.9 is used as a raw material, an acylation reaction can be performed in a homogeneous system. Compared with the case of using cellulose as a raw material, the reaction rate can be remarkably increased, and a cellulose mixed acylate having a uniform degree of substitution between molecules can be efficiently produced. In addition, an acyl group having a relatively high reactivity (for example, an acetyl group) is highly selectively selected at the 6-position (the most reactive position) of the glucose skeleton, and an acyl group having a relatively low reactivity (for example, It is possible to selectively introduce a benzoyl group) into the 2, 3 position of the glucose skeleton. Furthermore, in spite of introducing two kinds of acyl groups into the hydroxyl group in the molecule, it is possible to obtain a cellulose mixed acylate in one pot without isolating the reaction intermediate product in the middle, and the process can be shortened. Complex operations can be omitted. Even if a certain amount of water is present in the system, the first carboxylic acid can be converted into a first carboxylic acid using an acylating agent according to a predetermined amount of the first carboxylic acid (for example, acetic acid) regardless of the water content. A cellulose mixed acylate having a desired degree of substitution of the corresponding acyl group can be obtained. This is because, even when the acylating agent related to the first carboxylic acid is hydrolyzed by moisture in the system to form a carboxylic acid, the acylating agent related to the second carboxylic acid (for example, benzoic acid). This is because a mixed acid anhydride is produced by reacting with the acid, and this mixed acid anhydride acts as an acylating agent related to the first carboxylic acid. Moreover, according to the manufacturing method of this invention, the novel cellulose mixed acylate of this invention can be manufactured industrially efficiently.

  The present invention also provides a novel cellulose mixed acylate. This cellulose mixed acylate is excellent in various properties, particularly optical properties, for example, properties related to orientation birefringence and photoelastic coefficient when stretched into a film. Therefore, it can be suitably used as an optical material or the like.

  [Production of cellulose mixed acylate]

  In the production method of the present invention, when cellulose acetate is used as a raw material and a plurality of acyl groups having different reactivities are introduced into hydroxyl groups in the raw material, one acyl group is introduced in preference to the 6-position of the glucose skeleton, Industrially efficient production of cellulose acylates in which acyl groups are introduced mainly at the 2nd and 3rd positions of the glucose skeleton and the acyl group has a high total substitution frequency and specific acyl groups are selectively introduced at specific positions. It is a method to do.

  In the production method of the present invention, a plurality of acyl groups having different reactivities are introduced into cellulose acetate having a total acetyl group substitution degree of 1.5 to 2.9 so that the total acyl group substitution degree is 2.7 to 3. When the cellulose mixed acylate is 0.0, the raw material cellulose acetate corresponds to (i) the first carboxylic acid corresponding to the acyl group having relatively high reactivity and the acyl group having relatively low reactivity. The mixed acid anhydride with the second carboxylic acid is reacted with the acid anhydride or acid halide derivative of the second carboxylic acid, or (ii) the first corresponding to the acyl group having relatively high reactivity. Or the acid halide derivative of the second carboxylic acid corresponding to the acyl group having relatively low reactivity, or (iii) the first corresponding to the acyl group having relatively high reactivity. Carboxylic acid anhydride Is an acid anhydride derivative or acid halide derivative of a second carboxylic acid corresponding to an acyl group having a relatively low reactivity, without reacting an acid halide derivative and then performing a quench treatment or a reaction product isolation treatment To preferentially introduce the acyl group having relatively high reactivity at the 6-position of the glucose skeleton.

  In the present specification, the “acyl group having relatively high reactivity” means that a mixed acid anhydride formed from two types of acyl groups is reacted with a cellulose derivative having a hydroxyl group (particularly cellulose acetate). , Refers to an acyl group that is preferentially introduced into the glucopyranose ring.

  In the present invention, since cellulose acetate having a total substitution degree of acetyl group of 1.5 to 2.9 is used as a raw material, the raw material is easily dissolved in an organic solvent, and an acylation reaction can be performed in a uniform system. Therefore, compared with the case of acylating using cellulose as a raw material, variation in the degree of substitution distribution between molecules can be reduced, and a cellulose mixed acylate having a uniform degree of substitution distribution can be obtained. The total degree of acetyl group substitution of cellulose acetate used as a raw material is preferably 1.7 to 2.7, more preferably 1.9 to 2.5.

  The acyl group includes a saturated aliphatic acyl group, an aromatic acyl group, an unsaturated aliphatic acyl group (including those having an aromatic ring), and the like. The reactivity of the acyl group is mainly determined by electron withdrawing property and steric hindrance (bulkness). In general, an acyl group having a lower electron-withdrawing property has a higher reactivity, but if it is bulky, the reactivity is lowered. The order of reactivity of representative acyl groups is as follows: acetyl group> benzoyl group, propionyl group> benzoyl group, butyryl group> benzoyl group, acetyl group> propionyl group. Therefore, according to the present invention, for example, a saturated aliphatic carboxylic acid such as acetic acid or propionic acid (for example, a saturated aliphatic carboxylic acid having 2 to 4 carbon atoms, particularly acetic acid) is selected as the first carboxylic acid. By selecting an aromatic carboxylic acid such as benzoic acid as the second carboxylic acid, a saturated aliphatic acyl group is selectively introduced at the 6-position, and the aromatic acyl group is at the 2-position and the 3-position. The cellulose acylate selectively introduced can be efficiently produced.

  As a saturated aliphatic acyl group, C1-C10 saturated aliphatic acyl groups, such as an acetyl group, a propionyl group, a butyryl group, a pentanoyl group, a hexanoyl group, etc. are mentioned, for example. Saturated aliphatic carboxylic acids corresponding to these saturated aliphatic acyl groups are acetic acid, propionic acid, butyric acid, pentanoic acid, hexanoic acid, and the like.

  Examples of the aromatic ring in the aromatic acyl group include a benzene ring and a naphthalene ring. The aromatic ring may have a substituent. Examples of the substituent on the aromatic ring include a halogen atom, a cyano group, a hydroxyl group, a nitro group, a silyl group, a silyloxy group, and an alkyl group having 1 to 12 carbon atoms (methyl, ethyl, propyl, isopropyl, butyl, t-butyl). Group), C1-C12 alkoxy group (methoxy, ethoxy, propoxy group, etc.), C6-C20 aryl group (phenyl, naphthyl group, etc.), C6-C20 aryloxy group (phenyloxy) , Naphthyloxy group, etc.), C1-20 acyl group (acetyl, propionyl, benzoyl group, etc.), C1-20 substituted or unsubstituted carbamoyl group, C1-20 substituted or unsubstituted carbamoyloxy. Group, sulfamoyl group having 1 to 20 carbon atoms, sulfamoyloxy group having 1 to 20 carbon atoms, phosphino group, phosphinyl group, Suphono group, phosphinyloxy group, phosphonooxy group, phosphinylamino group, phosphonoamino group, ureido group having 1 to 20 carbon atoms, carboxyl group, substituted oxycarbonyl group having 1 to 20 carbon atoms (alkoxycarbonyl group, aryloxy Carbonyl group, aralkyloxycarbonyl group, etc.).

  Representative examples of the aromatic acyl group include benzoyl group, naphthoyl group, m-methylbenzoyl group, p-methylbenzoyl group, m-methoxybenzoyl group, p-methoxybenzoyl group, 3,5-dimethoxybenzoyl group, 3 , 4,5-trimethoxybenzoyl group, 2,4,6-trimethylbenzoyl group, m-cyanobenzoyl group, p-cyanobenzoyl group, m-chlorobenzoyl group, p-chlorobenzoyl group, m-fluorobenzoyl group, p-fluorobenzoyl group, 2,5-dichlorobenzoyl group, p-acetylbenzoyl group, p-phenylbenzoyl group, p-formylbenzoyl group, p-t-butylbenzoyl group, p-butoxybenzoyl group, m-acetoxybenzoyl Group, p-acetoxybenzoyl group, m-methoxycarbonylbenzoyl P-methoxycarbonylbenzoyl group, m-benzyloxybenzoyl group, p-benzyloxybenzoyl group, p-cyclohexylbenzoyl group, p-methanesulfonylaminobenzoyl group, p-nitrobenzoyl group, m-nitrobenzoyl group, m- Acetaminobenzoyl group, p-acetaminobenzoyl group, m-benzoylaminobenzoyl group, p-benzoylaminobenzoyl group, m-benzoyloxybenzoyl group, p-benzoyloxybenzoyl group, m-benzylbenzoyl group, p-benzylbenzoyl Group, m- (N-phenylcarbamoyloxy) benzoyl group, p- (N-phenylcarbamoyloxy) benzoyl group, p- (ethoxycarbonylamino) benzoyl group, p-methylthiobenzoyl group, p-phenylthio Nzoiru group, p- hydroxybenzoyl group, p- (4-pyridyl) benzoyl group. Among these, a benzoyl group is particularly preferable.

  Examples of the unsaturated aliphatic acyl group include a (meth) acryloyl group and a cinnamoyl group. Unsaturated aliphatic carboxylic acids corresponding to these unsaturated aliphatic acyl groups are (meth) acrylic acid, cinnamic acid and the like.

  Examples of the mixed acid anhydride of the first carboxylic acid and the second carboxylic acid in the above (i) include, for example, acetic acid benzoic acid mixed acid anhydride, acetic acid m-methylbenzoic acid mixed acid anhydride, and p-methyl acetate. Saturated aliphatic such as benzoic acid mixed acid anhydride, acetic acid cinnamic acid mixed acid anhydride, acetic acid 1-naphthylcarboxylic acid mixed acid anhydride, acetic acid 2-naphthylcarboxylic acid mixed acid anhydride, propionic acid benzoic acid mixed acid anhydride Examples thereof include mixed acid anhydrides of carboxylic acid and aromatic carboxylic acid. In a mixed acid anhydride of a saturated aliphatic carboxylic acid and an aromatic carboxylic acid, generally, the saturated aliphatic carboxylic acid corresponds to the first carboxylic acid, and the aromatic carboxylic acid corresponds to the second carboxylic acid. There are many.

  Examples of the acid anhydride or acid halide derivative of the second carboxylic acid in the above (i) include, for example, benzoic anhydride, m-methylbenzoic anhydride, p-methylbenzoic anhydride, cinnamic anhydride, and 1-naphthylcarboxylic anhydride. Acid, acid anhydride derivatives of aromatic carboxylic acid or unsaturated aliphatic carboxylic acid such as 2-naphthylcarboxylic anhydride; benzoic acid chloride, m-methylbenzoic acid chloride, p-methylbenzoic acid chloride, cinnamic acid chloride, 1 -Acid halide derivatives of aromatic carboxylic acids or unsaturated aliphatic carboxylic acids such as naphthyl carboxylic acid chloride and 2-naphthyl carboxylic acid chloride.

  In said (i), the mixed acid anhydride of 1st carboxylic acid and 2nd carboxylic acid acts as an acylating agent corresponding to 1st carboxylic acid. The acylating agent is more reactive than the acid anhydride or acid halide derivative of the second carboxylic acid, which acts as an acylating agent corresponding to the second carboxylic acid. On the other hand, the reactivity of hydroxyl groups at the 2nd, 3rd and 6th positions of the glucose skeleton of the raw material cellulose acetate is in the order of 6th position> 2nd position and 3rd position. Therefore, first, the hydroxyl group at the 6-position reacts with the mixed acid anhydride, and the acyl group corresponding to the first carboxylic acid is preferentially introduced at the 6-position. Then, the remaining hydroxyl groups (the remaining 6-position hydroxyl group and the 2-position, 3-position hydroxyl group) react with the acid anhydride or acid halide derivative of the second carboxylic acid, and the acyl group corresponding to the second carboxylic acid Is introduced at that position. Therefore, by selecting the amount of the mixed acid anhydride of the first carboxylic acid and the second carboxylic acid and the amount of the acid anhydride or acid halide derivative of the second carboxylic acid, the degree of substitution (first It is possible to control the substitution degree of the acyl group corresponding to the carboxylic acid, the substitution degree of the acyl group corresponding to the second carboxylic acid, and the total substitution degree of the acyl group), and the substituent distribution.

  When the raw material cellulose acetate contains moisture, the amount of the mixed acid anhydride of the first carboxylic acid and the second carboxylic acid need not be adjusted by the moisture. The reason is as follows. Even if the mixed acid anhydride is hydrolyzed to the first carboxylic acid and the second carboxylic acid with water, the acid anhydride or acid halide derivative of the second carboxylic acid is added to the system to some extent. In this case, the first carboxylic acid produced by hydrolysis reacts with the acid anhydride or acid halide derivative of the second carboxylic acid, thereby mixing a mixed acid anhydride of the first carboxylic acid and the second carboxylic acid. This is because it acts as an acylating agent corresponding to the first carboxylic acid. Therefore, even when the raw material cellulose acetate contains water, the mixed acid anhydride corresponding to the desired introduction amount is used regardless of the water content, thereby corresponding to the desired first carboxylic acid. It is possible to produce a cellulose mixed acylate having an acyl group substitution degree.

  Examples of the first carboxylic acid in (ii) include saturated aliphatic carboxylic acids having about 1 to 10 carbon atoms such as acetic acid, propionic acid, butyric acid, pentanoic acid and hexanoic acid. Examples of the acid halide derivative of the second carboxylic acid include benzoic acid chloride, m-methylbenzoic acid chloride, p-methylbenzoic acid chloride, cinnamic acid chloride, 1-naphthylcarboxylic acid chloride, and 2-naphthylcarboxylic acid. An aromatic carboxylic acid such as chloride or an acid halide derivative of an unsaturated aliphatic carboxylic acid can be used.

  In (ii), when the first carboxylic acid reacts with the acid halide derivative of the second carboxylic acid, a mixed acid anhydride of the first carboxylic acid and the second carboxylic acid is generated. The embodiment of is substantially the same as the embodiment of (i).

  That is, the first carboxylic acid reacts with the acid halide derivative of the second carboxylic acid to produce a mixed acid anhydride of the first carboxylic acid and the second carboxylic acid, and this mixed acid anhydride is Acts as an acylating agent corresponding to one carboxylic acid. This acylating agent is more reactive than the acid halide derivative of the second carboxylic acid, which acts as an acylating agent corresponding to the second carboxylic acid. Accordingly, as in the case (i), first, the hydroxyl group at the 6-position reacts with the mixed acid anhydride, and the acyl group corresponding to the first carboxylic acid is preferentially introduced at the 6-position. Then, the remaining hydroxyl groups (the remaining 6-position hydroxyl group and the 2-position, 3-position hydroxyl group) react with the acid halide derivative of the second carboxylic acid, and the acyl group corresponding to the second carboxylic acid is in that position. be introduced. Therefore, by selecting the amount of the first carboxylic acid and the amount of the acid halide derivative of the second carboxylic acid, the substitution degree (the substitution degree of the acyl group corresponding to the first carboxylic acid, the second carboxylic acid, It becomes possible to control the substitution degree of the acyl group corresponding to the acid and the total substitution degree of the acyl group) and the substituent distribution.

  Moreover, when the raw material cellulose acetate contains moisture, the amount of the first carboxylic acid used need not be adjusted by the moisture. The reason is the same as described above. That is, if the acid halide derivative of the second carboxylic acid is added to some extent in the system, the mixed acid anhydride formed by the reaction between the first carboxylic acid and the acid halide derivative of the second carboxylic acid. Acts as an acylating agent corresponding to the first carboxylic acid. Therefore, even when the raw material cellulose acetate contains water, the first carboxylic acid in an amount corresponding to the desired introduction amount is used regardless of the water content, thereby corresponding to the desired first carboxylic acid. It is possible to produce a mixed cellulose acylate having an acyl group substitution degree.

  The acid anhydride or acid halide derivative of the first carboxylic acid in (iii) is, for example, saturated with about 1 to 10 carbon atoms such as acetic anhydride, propionic anhydride, butyric anhydride, pentanoic anhydride, hexanoic anhydride, etc. Examples thereof include acid anhydride derivatives of aliphatic carboxylic acids; acid halide derivatives of saturated aliphatic carboxylic acids having about 1 to 10 carbon atoms such as acetic acid chloride, propionic acid chloride, butyric acid chloride, pentanoic acid chloride, and hexanoic acid chloride.

  Examples of the acid anhydride or acid halide derivative of the second carboxylic acid in (iii) include, for example, benzoic anhydride, m-methylbenzoic anhydride, p-methylbenzoic anhydride, cinnamic anhydride, and 1-naphthylcarboxylic anhydride. , Aromatic carboxylic acids such as 2-naphthylcarboxylic anhydride or acid anhydride derivatives of unsaturated aliphatic carboxylic acids; benzoic acid chloride, m-methylbenzoic acid chloride, p-methylbenzoic acid chloride, cinnamic acid chloride, 1- Examples thereof include aromatic carboxylic acids such as naphthylcarboxylic acid chloride and 2-naphthylcarboxylic acid chloride, and acid halide derivatives of unsaturated aliphatic carboxylic acids.

  In the above (iii), the acid anhydride or acid halide derivative of the first carboxylic acid acts as an acylating agent corresponding to the first carboxylic acid. On the other hand, as described above, the reactivity of the hydroxyl groups at the 2nd, 3rd and 6th positions of the glucose skeleton of the raw material cellulose acetate is in the order of 6th position> 2nd position and 3rd position. Therefore, first, the hydroxyl group at the 6-position reacts with the acid anhydride or acid halide derivative of the first carboxylic acid, and the acyl group corresponding to the first carboxylic acid is preferentially introduced at the 6-position. Then, the remaining hydroxyl groups (the remaining 6-position hydroxyl group and the 2-position, 3-position hydroxyl group) react with the acid anhydride or acid halide derivative of the second carboxylic acid supplied next, and the second carboxyl An acyl group corresponding to the acid is introduced at that position. Therefore, by selecting the amount of the acid anhydride or acid halide derivative of the first carboxylic acid and the amount of the acid anhydride or acid halide derivative of the second carboxylic acid, the degree of substitution (into the first carboxylic acid) It becomes possible to control the substitution degree of the corresponding acyl group, the substitution degree of the acyl group corresponding to the second carboxylic acid, and the total substitution degree of the acyl group) and the substituent distribution.

  When the raw material cellulose acetate contains moisture, the amount of the first carboxylic acid anhydride or acid halide derivative does not need to be adjusted by the moisture. The reason is as follows. Even if the acid anhydride or acid halide derivative of the first carboxylic acid is hydrolyzed to the first carboxylic acid with water, the previous reaction (acylation with the acid anhydride or acid halide derivative of the first carboxylic acid) After the reaction, the reaction proceeds to the subsequent reaction (acylation reaction with the acid anhydride or acid halide derivative of the second carboxylic acid) without quenching or isolation of the reaction product. If the acid anhydride or acid halide derivative of 2 carboxylic acid is added to some extent, the first carboxylic acid generated by hydrolysis reacts with the acid anhydride or acid halide derivative of the second carboxylic acid, This is because it is regenerated into a mixed acid anhydride of the first carboxylic acid and the second carboxylic acid and acts as an acylating agent corresponding to the first carboxylic acid. Therefore, even when the raw material cellulose acetate contains water, the use of the acid anhydride or acid halide derivative of the first carboxylic acid in an amount commensurate with the desired introduction amount is possible regardless of the water content. It is possible to produce a cellulose mixed acylate having an acyl group substitution degree corresponding to the first carboxylic acid.

  In the case of (iii), 1 mol of the acid halide derivative of the first carboxylic acid functions as an acylating agent for 1 mol, but 1 mol of the acid anhydride derivative of the first carboxylic acid is 2 Functions as a molar acylating agent. This is because, when an acid anhydride derivative of the first carboxylic acid is used, an acid anhydride or acid halide derivative of the second carboxylic acid to be added later in the first carboxylic acid by-produced by acylation This is because the reaction generates a mixed acid anhydride of the first carboxylic acid and the second carboxylic acid, and this mixed acid anhydride acts as an acylating agent corresponding to the first carboxylic acid. Therefore, when 1 mol of hydroxyl group is acylated with an acyl group corresponding to the first carboxylic acid, 1 mol is required when an acid halide derivative of the first carboxylic acid is used as an acylating agent. When an acid anhydride derivative of the first carboxylic acid is used as the agent, 0.5 mol is sufficient.

  In the present invention, it is preferred that the first carboxylic acid is a saturated aliphatic carboxylic acid and the second carboxylic acid is an aromatic carboxylic acid. Moreover, as a 1st carboxylic acid, a C2-C4 saturated aliphatic carboxylic acid is preferable and an acetic acid is especially preferable.

  In each of the embodiments (i) to (iii), the reaction solvent is not particularly limited as long as it is a solvent that is excellent in the solubility of raw materials and products and does not inhibit the reaction, and is appropriately selected depending on the type of raw materials and the like. it can. Examples of such solvents include ketone solvents such as acetone, methyl ethyl ketone, cyclohexanone, and isophorone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and methyl formate; pyridine, N, N-dimethylformamide, Nitrogen-containing compounds such as N, N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, nitromethane; ethers such as tetrahydrofuran, dioxane, dioxolane (cyclic ethers, chain ethers); methylene chloride, chloroform, dichloroethane, tetrachloroethane And halogenated hydrocarbons such as carbon tetrachloride; sulfur-containing compounds such as dimethyl sulfoxide. Among these, pyridine, methylene chloride, chloroform, and cyclohexanone are preferable from the viewpoint of solubility of raw materials and products, and pyridine is particularly preferable. A solvent can be used individually or in combination of 2 or more types.

  The concentration of the raw material cellulose acetate to be subjected to the acylation reaction can be appropriately selected in consideration of solubility, reaction efficiency, and the like, but is generally 2 to 50% by weight, preferably about 5 to 20% by weight.

  In the above (i), the usage amount of the mixed acid anhydride of the first carboxylic acid and the second carboxylic acid is appropriately selected according to the introduction amount of the acyl group corresponding to the desired first carboxylic acid. For example, when it is desired to introduce an acyl group corresponding to the first carboxylic acid into all of the hydroxyl groups at the 6-position of the raw cellulose acetate, and to introduce an acyl group corresponding to the second carboxylic acid into the 2- and 3-position hydroxyl groups In this case, it is preferable to use about 0.95 to 1.2 mol of a mixed acid anhydride per 1 mol of the hydroxyl group at the 6-position.

  In (i), the use amount of the acid anhydride or acid halide derivative of the second carboxylic acid is appropriately selected according to the amount of acyl group introduced corresponding to the desired second carboxylic acid. For example, an acyl group corresponding to the first carboxylic acid is introduced into all of the 6-position hydroxyl groups of the raw material cellulose acetate, and an acyl group corresponding to the second carboxylic acid is introduced into all of the 2-position and 3-position hydroxyl groups. In this case, it is preferable to use an acid anhydride or acid halide derivative of 1 to 5 mol, particularly about 1 to 3 mol of the second carboxylic acid with respect to 1 mol in total of the hydroxyl groups at the 2nd and 3rd positions. . In addition, when the raw material cellulose acetate contains moisture, it is preferable to set the usage amount of the acid anhydride or acid halide derivative of the second carboxylic acid in anticipation of the amount decomposed by the moisture.

  In said (ii), the usage-amount of 1st carboxylic acid is suitably selected according to the introduction amount of the acyl group corresponding to the desired 1st carboxylic acid. For example, when it is desired to introduce an acyl group corresponding to the first carboxylic acid into all of the hydroxyl groups at the 6-position of the raw cellulose acetate, and to introduce an acyl group corresponding to the second carboxylic acid into the 2- and 3-position hydroxyl groups In this case, it is preferable to use about 0.95 to 1.2 mol of the first carboxylic acid with respect to 1 mol of the hydroxyl group at the 6-position.

  In (ii), the amount of the acid halide derivative of the second carboxylic acid used is appropriately selected according to the amount of acyl group introduced corresponding to the desired second carboxylic acid. In addition, since the acid halide derivative of the second carboxylic acid reacts with the first carboxylic acid to form a mixed acid anhydride, the acid halide derivative of the second carboxylic acid is based on 1 mol of the first carboxylic acid. More than 1 mole is required. For example, an acyl group corresponding to the first carboxylic acid is introduced into all of the 6-position hydroxyl groups of the raw material cellulose acetate, and an acyl group corresponding to the second carboxylic acid is introduced into all of the 2-position and 3-position hydroxyl groups. In this case, it is preferable to use an acid halide derivative of the second carboxylic acid in an amount of 1 to 5 mol, particularly about 1 to 3 mol with respect to 1 mol of the total of the hydroxyl groups at the 2nd and 3rd positions. In addition, when the raw material cellulose acetate contains moisture, it is preferable to set the usage amount of the acid halide derivative of the second carboxylic acid in anticipation of the amount decomposed by the moisture.

  In the above (iii), the amount of the first carboxylic acid anhydride or acid halide derivative used in the reaction of the cellulose acetate and the first carboxylic acid anhydride or acid halide derivative in the preceding stage is the desired amount. It is appropriately selected according to the amount of acyl group introduced corresponding to one carboxylic acid. For example, when it is desired to introduce an acyl group corresponding to the first carboxylic acid into all of the hydroxyl groups at the 6-position of the raw cellulose acetate, and to introduce an acyl group corresponding to the second carboxylic acid into the 2- and 3-position hydroxyl groups In this case, the acid anhydride derivative of the first carboxylic acid is about 0.48 to 0.6 mol, and the acid halide derivative of the first carboxylic acid is 0.95 to 1 with respect to 1 mol of the hydroxyl group at the 6-position. It is preferable to use about 2 moles.

  In (iii), after the acetylation in the previous stage, the acetylation in the subsequent stage is performed without performing the quenching process or the isolation process of the reaction product. The quench treatment means that the remaining acylating agent is deactivated by adding water or alcohol to the reaction mixture.

  The use amount of the acid anhydride or acid halide derivative of the second carboxylic acid in the latter stage in (iii) is appropriately selected according to the introduction amount of the acyl group corresponding to the desired second carboxylic acid. For example, an acyl group corresponding to the first carboxylic acid is introduced into all of the 6-position hydroxyl groups of the raw material cellulose acetate, and an acyl group corresponding to the second carboxylic acid is introduced into all of the 2-position and 3-position hydroxyl groups. In this case, it is preferable to use an acid anhydride or acid halide derivative of 1 to 5 mol, particularly about 1 to 3 mol of the second carboxylic acid with respect to 1 mol in total of the hydroxyl groups at the 2nd and 3rd positions. . In addition, when the raw material cellulose acetate contains moisture, it is preferable to set the usage amount of the acid anhydride or acid halide derivative of the second carboxylic acid in anticipation of the amount decomposed by the moisture.

  In the production method of the present invention, in any of the cases (i) to (iii), an acylating agent (a mixed acid anhydride of a first carboxylic acid and a second carboxylic acid, a first carboxylic acid, a first carboxylic acid, There are no particular restrictions on the method of addition of the acid anhydride or acid halide derivative of the first carboxylic acid, or the acid anhydride or acid halide derivative of the second carboxylic acid) to the reaction system, and they may be added all at once. In order to control the reaction, it is preferable to add sequentially (added continuously or intermittently).

  If necessary, a base may be added to the reaction system in order to promote the reaction and capture the generated hydrogen halide and the like. Examples of the base include nitrogen-containing aromatic compounds such as pyridine and dimethylaminopyridine, tertiary amines such as triethylamine, tri-n-butylamine and tri-propylamine, and inorganic bases. Pyridine and the like can be used as a solvent as described above.

  The reaction temperature in the acylation reaction varies depending on the type of raw material, but is usually 0 to 150 ° C., preferably about 30 to 130 ° C.

  By the acylation reaction, an acyl group corresponding to the first carboxylic acid is selectively introduced into the 6-position of the glucose skeleton, and an acyl group corresponding to the second carboxylic acid is selectively introduced into the 2-position and the 3-position. A high acyl group substitution degree cellulose mixed acylate is produced.

  After completion of the reaction, alcohol is added to the reaction mixture, and the remaining highly reactive acylating agent (acid halide, acid anhydride) is converted into an ester with extremely low reactivity and high solubility in water and organic solvents. It is preferable to convert to By converting the excess acylating agent to an ester in this manner, impurities derived from the acylating agent, for example, a compound having low solubility in water or an organic solvent such as carboxylic acid which is a hydrolysis product of the acylating agent, It is possible to prevent troubles such as coloring and white turbidity of products due to other impurities, interference of function expression, mixing of impurities into products, etc., and obtaining high purity and high quality cellulose mixed acylate industrially efficiently. It becomes possible.

  Examples of the alcohol include methanol, ethanol, propanol, isopropyl alcohol, butanol, 2-butanol, isobutyl alcohol, s-butyl alcohol, t-butyl alcohol, pentanol, 2-pentanol, 3-pentanol, hexanol, Monohydric alcohols such as octanol, cyclopentyl alcohol, cyclohexyl alcohol, and benzyl alcohol; polyhydric alcohols such as ethylene glycol and glycerin can be used. Among these, alcohols having 1 to 5 carbon atoms such as methanol, ethanol, propanol, isopropyl alcohol, butanol, 2-butanol, t-butyl alcohol, pentanol, 2-pentanol, and 3-pentanol are preferable.

  The amount of alcohol used may be an amount necessary for esterifying all of the remaining excess acylating agent. For example, 1 to 20 mol, preferably 1 mol per 1 mol of the remaining excess acylating agent. About 1.5 to 10 moles. If the amount of alcohol is too small, the acylating agent may remain without being completely esterified, and if the amount of alcohol is too large, the produced cellulose mixed acylate may precipitate. If the cellulose mixed acylate precipitates at this stage, impurities are easily taken in. Therefore, the esterification reaction of the remaining acylating agent is preferably performed under a condition that does not precipitate the produced cellulose mixed acylate (in a homogeneous system).

  The reaction temperature in the reaction between the alcohol and the remaining excess acylating agent can be appropriately selected according to the type of the cellulose acylate to be added and the type of alcohol to be added. Is usually 80 ° C. or lower, preferably 60 ° C. or lower, more preferably 50 ° C. or lower. The minimum of reaction temperature should just be a temperature which does not impair progress of reaction, for example, 30 degreeC, Preferably it is 40 degreeC. The reaction time varies depending on the reaction temperature and the like, but is generally about 0.1 to 12 hours, preferably about 0.1 to 3 hours.

  From the reaction mixture after the acylation reaction, if necessary, an excess acylating agent is esterified as described above, and then the cellulose acylate as a target product is separated. The method for separating cellulose mixed acylate is not particularly limited, and for example, precipitation, crystallization, filtration, washing, drying, extraction, concentration, column chromatography and the like can be used alone or in appropriate combination of two or more. In view of operability and purification efficiency, a method of separating the cellulose mixed acylate by precipitation (including reprecipitation) is particularly preferable. The precipitation operation is performed by mixing the solution containing the cellulose mixed acylate with the poor solvent, such as pouring the solution containing the produced cellulose mixed acylate into the poor solvent of the cellulose mixed acylate. Examples of the solvent of the solution containing cellulose mixed acylate (good solvent for cellulose mixed acylate) include nitrogen-containing heterocyclic compounds such as pyridine, ketones such as acetone, halogenated hydrocarbons such as methylene chloride, esters, ethers, amides, Examples include aprotic polar solvents. These solvents can be used alone or in combination of two or more. As the solvent, nitrogen-containing heterocyclic compounds such as pyridine, ketones such as acetone, and halogenated hydrocarbons such as methylene chloride are particularly preferable.

  As a poor solvent for cellulose mixed acylate, a solvent having low solubility of cellulose mixed acylate may be used. For example, methanol, ethanol, propanol, isopropyl alcohol, butanol, 2-butanol, t-butyl alcohol, pentanol, 2-pen Examples thereof include alcohols having 1 to 5 carbon atoms such as tanol and 3-pentanol (particularly monohydric alcohols); water; aliphatic hydrocarbons such as hexane; alicyclic hydrocarbons such as cyclohexane. These solvents can be used alone or in combination of two or more. Examples of a combination of two or more solvents include a mixed solution of two or more types of alcohol having 1 to 5 carbon atoms, a mixed solution of alcohol having 1 to 5 carbon atoms and water, and the like. As the poor solvent, alcohol having 1 to 5 carbon atoms is particularly preferable.

  The amount of the poor solvent used in the precipitation operation is, for example, 50 to 20000 parts by weight, preferably 100 to 10,000 parts by weight, and more preferably 150 to 1000 parts by weight with respect to 100 parts by weight of the cellulose mixed acylate solution. . If the amount of the poor solvent is too small, it may be difficult to efficiently obtain a high-quality cellulose mixed acylate. Conversely, if the amount of the poor solvent is too large, it is economically disadvantageous.

  The precipitated cellulose mixed acylate is subjected to solid-liquid separation operations such as filtration and centrifugation, and the obtained solid is subjected to reprecipitation as necessary, followed by drying to obtain high-purity and high-quality cellulose. Mixed acylates can be obtained.

  As a method for purifying cellulose mixed acylate, cellulose mixed acylate powder (for example, obtained by the above precipitation operation), cellulose mixed acylate is difficult to dissolve, ester produced by reaction of acylating agent and alcohol, etc. A method of washing (extracting) these impurities with a solvent that is easily dissolved is also preferred. As such a solvent, the solvent illustrated as a poor solvent of the said cellulose mixed acylate is mentioned. Among these, the said C1-C5 alcohol is preferable.

  Since the production method of the present invention does not require a sulfuric acid catalyst, the production of low molecular weight components can be suppressed, the molecular weight distribution can be reduced, and coloring of the product can be reduced. For example, by the method of the present invention, a cellulose mixed acylate having a coloring degree of 200 or less, more preferably 150 or less, and further preferably 100 or less in terms of the Hazen unit color number can be obtained.

  The cellulose mixed acylate obtained by the method of the present invention can be used as a material such as a fiber, an adsorbent, a film (especially an optical film), an optical isomer separating agent or the like as it is or further derivatized. Moreover, a function can be changed or a new function can be added by adding this cellulose mixed acylate or its derivative to another substance or material.

[Cellulose mixed acylate]
The cellulose mixed acylate of the present invention is a cellulose mixed acylate having a high acyl group substitution degree of 2.7 to 3.0 and a total acyl group substitution degree of 1.5 to 2.9. The total substitution degree of the acyl group having a lower reactivity is 0.1 to 1.5. The total degree of substitution with an acyl group is preferably 2.8 to 3.0, more preferably 2.9 to 3.0. The total degree of substitution with an acetyl group is preferably 1.8 to 2.8, more preferably 2.2 to 2.7. The total degree of substitution with an acyl group that is less reactive than an acetyl group is 0.1 to 1.5, preferably 0.2 to 1.2, and more preferably 0.3 to 0.8.

  An important feature of the cellulose mixed acylate of the present invention is that the sum of the substitution degree at the 2-position with an acyl group having a reactivity lower than that of the acetyl group and the substitution degree at the 3-position with an acyl group having a reactivity lower than that of the acetyl group is Greater than twice the degree of substitution at the 6-position by an acyl group that is less reactive than the group (provided that all of the acyl groups that are less reactive than the acetyl groups at the 2-, 3- and 6-positions are aliphatic acyl groups) In this case, the sum of the degree of acyl group substitution that is less reactive than the acetyl group at the 2-position and the degree of acyl group substitution that is less reactive than the acetyl group at the 3-position is more reactive than the acetyl group at the 6-position. The acyl substitution degree is 1.3 times, preferably 1.38 times greater. It should be noted that, regardless of the type of acyl group that is less reactive than the acetyl group, the substitution degree at the 2-position by the acyl group that is less reactive than the acetyl group and the 3-position by the acyl group that is less reactive than the acetyl group It is preferable that the sum of the degree of substitution is greater than twice the degree of substitution at the 6-position with an acyl group that is less reactive than the acetyl group.

  Such a cellulose mixed acylate has an acyl group that is less reactive than an acetyl group in a relatively rich manner at the 2nd and 3rd positions as compared to the 6th position, and thus is superior to the conventional cellulose mixed acylate. It has characteristics. For example, when the acyl group having a lower reactivity than the acetyl group is an aromatic acyl group, when the polymer chain is oriented by stretching, the 2-position bonded to the glucopyranose ring only through the oxygen atom and It is considered that the aromatic ring of the aromatic acyl group introduced at the 3-position is arranged in a direction orthogonal to the polymer chain, and the polarizability due to the aromatic ring faces in the direction orthogonal to the polymer chain. Therefore, it is considered that the aromatic acyl group introduced into the 2nd and 3rd positions acts to make the orientation birefringence of the cellulose mixed acylate negative. On the other hand, the aromatic ring of the aromatic acyl group introduced at the 6-position bonded to the glucopyranose ring via the methyleneoxy group is highly flexible, so it is oriented in the same direction as the polymer chain, resulting from the aromatic ring The polarizability is considered to be in the direction parallel to the polymer chain. Therefore, it is considered that the aromatic acyl group introduced at the 6-position acts to make the orientation birefringence of the cellulose mixed acylate positive. For this reason, the cellulose acylate in which the aromatic acyl group is relatively rich in the 2nd and 3rd positions compared to the 6th position is a material having a high polarizability in the direction perpendicular to the polymer chain, and has a large birefringence. The direction which shows is orthogonal to the extending direction of the film (negative orientation birefringence). The distribution of the substitution positions of the aromatic acyl group is considered to affect the photoelastic birefringence. Therefore, the film comprising the cellulose mixed acylate of the present invention is useful as a retardation film, a protective film for a polarizing film, and the like. The above consideration is based on Sadao Fujii, “Required Properties and Material Design of Polymer Phase Retardation Film” (“Liquid Crystal”, Vol. 9, No. 4, 2005, pp. 227 to 236). Is. Further, even if the acyl group having a lower reactivity than the acetyl group is a group other than the aromatic acyl group, the same or other actions as described above can be expected based on the distribution of substitution positions.

  The sum of the substitution degree at the 2-position by an acyl group having a lower reactivity than the acetyl group and the substitution degree at the 3-position by an acyl group having a lower reactivity than the acetyl group is due to the acyl group having a reactivity lower than that of the acetyl group. The substitution degree at the 6-position is preferably 2.5 times or more, more preferably 3.0 times or more.

  In the cellulose mixed acylate of the present invention, the substitution degree at the 2-position with the acyl group, the substitution degree at the 3-position with the acyl group, and the substitution degree at the 6-position with the acyl group are usually in the range of 0.9 to 1.0, respectively. . The sum of the substitution degree at the 2-position with an acyl group having a lower reactivity than the acetyl group and the substitution degree at the 3-position with an acyl group having a lower reactivity than the acetyl group is usually 0.1 to 1.0, preferably It is about 0.15 to 0.7, more preferably about 0.2 to 0.5. Furthermore, the substitution degree at the 6-position with an acyl group having a lower reactivity than the acetyl group is usually 0 to 0.5, preferably 0 to 0.3, more preferably 0 to 0.2 (for example, 0.01 to 0). .2) About. The degree of substitution at the 6-position with an acetyl group is usually 0.5 to 1.0, preferably 0.7 to 1.0, and more preferably 0.8 to 1.0.

  Examples of the acyl group having lower reactivity than the acetyl group include an aromatic acyl group, an unsaturated aliphatic acyl group, and a saturated aliphatic acyl group having an electron-withdrawing group. Of these, an aromatic acyl group is preferred. The aromatic ring in the aromatic acyl group may have a substituent.

  Examples of the aromatic ring in the aromatic acyl group include a benzene ring and a naphthalene ring. Examples of the substituent on the aromatic ring include a halogen atom, a cyano group, a hydroxyl group, a nitro group, a silyl group, a silyloxy group, and an alkyl group having 1 to 12 carbon atoms (methyl, ethyl, propyl, isopropyl, butyl, t-butyl). Group), C1-C12 alkoxy group (methoxy, ethoxy, propoxy group, etc.), C6-C20 aryl group (phenyl, naphthyl group, etc.), C6-C20 aryloxy group (phenyloxy) , Naphthyloxy group, etc.), C1-20 acyl group (acetyl, propionyl, benzoyl group, etc.), C1-20 substituted or unsubstituted carbamoyl group, C1-20 substituted or unsubstituted carbamoyloxy. Group, sulfamoyl group having 1 to 20 carbon atoms, sulfamoyloxy group having 1 to 20 carbon atoms, phosphino group, phosphinyl group, Suphono group, phosphinyloxy group, phosphonooxy group, phosphinylamino group, phosphonoamino group, ureido group having 1 to 20 carbon atoms, carboxyl group, substituted oxycarbonyl group having 1 to 20 carbon atoms (alkoxycarbonyl group, aryloxy Carbonyl group, aralkyloxycarbonyl group, etc.).

  Examples of the unsaturated aliphatic acyl group include a (meth) acryloyl group and a cinnamoyl group.

  Examples of the saturated aliphatic acyl group in the saturated aliphatic acyl group having an electron-withdrawing group include saturated aliphatic acyl groups having about 1 to 10 carbon atoms such as an acetyl group, a propionyl group, a butyryl group, a pentanoyl group, and a hexanoyl group. Can be mentioned. Examples of the electron-withdrawing group bonded to the saturated aliphatic acyl group include a halogen atom such as a fluorine atom, a cyano group, a nitro group, a substituted oxycarbonyl group (an alkoxycarbonyl group, an aryloxycarbonyl group, an aralkyl group). Oxycarbonyl group, etc.).

  Representative examples of acyl groups that are less reactive than acetyl groups include benzoyl, naphthoyl, m-methylbenzoyl, p-methylbenzoyl, m-methoxybenzoyl, p-methoxybenzoyl, 3, 5 -Dimethoxybenzoyl group, 3,4,5-trimethoxybenzoyl group, 2,4,6-trimethylbenzoyl group, m-cyanobenzoyl group, p-cyanobenzoyl group, m-chlorobenzoyl group, p-chlorobenzoyl group, m-fluorobenzoyl group, p-fluorobenzoyl group, 2,5-dichlorobenzoyl group, p-acetylbenzoyl group, p-phenylbenzoyl group, p-formylbenzoyl group, pt-butylbenzoyl group, p-butoxybenzoyl Group, m-acetoxybenzoyl group, p-acetoxybenzoyl group, m-methoxy Carbonylbenzoyl group, p-methoxycarbonylbenzoyl group, m-benzyloxybenzoyl group, p-benzyloxybenzoyl group, p-cyclohexylbenzoyl group, p-methanesulfonylaminobenzoyl group, p-nitrobenzoyl group, m-nitrobenzoyl group M-acetaminobenzoyl group, p-acetaminobenzoyl group, m-benzoylaminobenzoyl group, p-benzoylaminobenzoyl group, m-benzoyloxybenzoyl group, p-benzoyloxybenzoyl group, m-benzylbenzoyl group, p -Benzylbenzoyl group, m- (N-phenylcarbamoyloxy) benzoyl group, p- (N-phenylcarbamoyloxy) benzoyl group, p- (ethoxycarbonylamino) benzoyl group, p-methylthiobenzoy Group, p- phenylthiobenzoyl group, p- hydroxybenzoyl group, p- (4-pyridyl) benzoyl group, cinnamoyl group, trifluoroacetyl group, monochloroacetyl acetyl group, etc. trichloroacetyl group. Among these, a benzoyl group is particularly preferable.

  In the cellulose mixed acylate of the present invention, the sulfate group content is, for example, 200 ppm by weight or less (eg 1 to 200 ppm by weight), preferably 150 ppm by weight or less (eg 1 to 150 ppm by weight) with respect to the cellulose mixed acylate. ), More preferably 100 ppm by weight or less (for example, 1 to 100 ppm by weight), and particularly preferably 50 ppm by weight or less (for example, 1 to 50 ppm by weight). If a large amount of sulfate radicals remain, problems such as yellowing of the product color may occur when the product is dried or changes with time. In addition, there is a possibility of causing a functional inhibition.

The sulfate radical here means the total quantity of sulfate radicals present in the cellulose mixed acylate in the form of bound sulfuric acid, unbound sulfuric acid, sulfate, sulfate ester, sulfate complex, and the like. The content of sulfate radicals in the cellulose mixed acylate was determined by calcining an absolutely dry sample (cellulose mixed acylate) in an electric furnace at 1300 ° C, trapping the sublimed sulfurous acid gas in 10% by weight hydrogen peroxide, and measuring the coulometry. It can be measured by quantifying by a method (SO ₄ ^2- converted value). The unit is ppm by weight with respect to cellulose mixed acylate. The analysis conditions of the coulometric titration method are as follows. As an apparatus used for the coulometric titration method, for example, trade name “TOX-10Σ” manufactured by Mitsubishi Chemical Corporation may be mentioned.
Temperature: 1100 ° C
Sample amount: 20 ± 2mg
Combustion gas: Oxygen gas (99.7% or more)
Aeration rate: argon 200 ml / min, oxygen 150 ml / min
Combustion tube: quartz glass tube (inner tube inner diameter 13 mm, outer tube inner diameter 22 mm)

  The cellulose mixed acylate of the present invention is an acetylating agent (for example, acetic anhydride, acetic acid chloride) as an acylating agent for introducing an acyl group corresponding to the first carboxylic acid in the method for producing a cellulose mixed acylate of the present invention. Etc.) can be efficiently produced. According to this production method, since it is not necessary to use sulfuric acid, it is possible to obtain a cellulose mixed acylate having a very low sulfate radical content as described above.

  The cellulose mixed acylate of the present invention is excellent in various properties, particularly optical properties, for example, properties relating to orientation birefringence and photoelastic coefficient when stretched into a film. Therefore, it can be used as an optical material or the like.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In Examples and Comparative Examples, “2-position Ac group” is 2-position acetyl group substitution degree, “3-position Ac group” is 3-position acetyl group substitution degree, and “6-position Ac group” is 6-position acetyl group substitution. “2-position Pr group” is the 2-position propionyl group substitution degree, “3-position Pr group” is the 3-position propionyl group substitution degree, “6-position Pr group” is the 6-position propionyl group substitution degree, “2-position Pr group” “Bz group” represents the degree of substitution of the benzoyl group at the 2-position, “3-position Bz group” represents the degree of substitution of the benzoyl group at the 3-position, and “6-position Bz group” represents the degree of substitution of the benzoyl group at the 6-position. “Ppm” means ppm by weight and chemical shift.

In addition, the measurement of the substitution degree of the acyl group (DS), the substitution degree of the 2-position of the glucose skeleton (DS2), the substitution degree of the 3-position of the glucose skeleton (DS3), and the substitution degree of the 6-position of the glucose skeleton (DS6) It carried out as follows. The measurement conditions are as shown below.
Measuring equipment: AVANCE600 manufactured by Bruker
Measurement mode: ¹ H-NMR, ¹³ C-NMR
Measuring solvent: deuterated chloroform (with TMS)
Measurement temperature: 40 ° C
The substituent distribution is determined from the signal of the carbonyl group into which the acyl group has been introduced. The shape of the signal changes depending on the type of substituent, degree of substitution, and the position where the substituent is introduced. In addition, it is necessary to measure the cellulose acylate. Although the exact position specifying method differs depending on the degree of substitution and the substituent distribution, the numerical value of the substituent distribution in the present example is calculated as follows.
For example, in the case of cellulose acetate benzoate, in pyridine solvent sample, after propionylated with propionic anhydride, the ¹ H-NMR spectrum in deuterochloroform solvent was measured, after calculating a degree of substitution of each substituent group, ¹³ C- The NMR spectrum was measured, and the signal of benzoylcarbonyl carbon appearing in the vicinity of 164 to 167 ppm was indicated by a point as shown in FIG. 1 (indicated by Δ in the figure. Signal trough positions; around 164.9 ppm and around 165.5 ppm) ) And defined as the integrated intensity of each benzoylcarbonyl carbon at positions 2, 3, and 6 from the high magnetic field side. The degree of benzoyl substitution DSBzi (i is 2, 3 or 6) at the i-position of the glucose skeleton was determined from the following formula. DSBz represents the total degree of substitution of benzoyl groups.
DSBzi = DSBz * (i-position benzoylcarbonyl carbon signal integral intensity) / (sum of 2,3 and 6-position benzoylcarbonyl carbon signal integral intensity)

  Further, the degree of coloring was measured based on the color of JIS-K0071-1 chemical product. That is, the dope obtained by dissolving 2.4 g of the product in 40 mL of a mixed solvent of methylene chloride / methanol = 90/10 is put into a colorimetric tube, and colored by comparing with the reference color described in the JIS standard. The degree (number of Hazen unit colors) was measured.

Production Example 1
Wood pulp having an α-cellulose content of 97% was crushed and dried to a moisture content of 5%. The pulverized pulp was supplied to a pretreatment device, 25 parts by weight of glacial acetic acid per 100 parts by weight of α-cellulose was added to the pulp, and the mixture was mixed at 50 ° C. for 30 minutes to activate the cellulose.
The activated cellulose was transferred to a kneader-type acetylation apparatus, and 280 parts by weight of acetic anhydride and 450 parts by weight of glacial acetic acid which had been cooled to 10 ° C. in advance were added to the acetylation apparatus. Then 5 parts by weight of concentrated sulfuric acid was added and the whole mixture was mixed. Since heat accumulates in the contents of the reaction, acetylation is performed while controlling the temperature of the system by cooling so that the temperature of the system rises from the initial temperature of 10 ° C. to 68 ° C. over a period of 50 minutes at a substantially constant rate. The temperature of the system was maintained at 68 ° C. for 10 minutes.
To the system at 68 ° C., 24 parts by weight of 20 wt% magnesium acetate aqueous solution was added. The amount of magnesium acetate added was stoichiometrically excessive from the amount required for neutralization of sulfuric acid in the system. The completely neutralized mixture was transferred to an autoclave, and steam with a gauge pressure of 5 kg / cm ² was blown into the mixture while stirring the mixture and heated to 120 ° C. The mixture was kept at this temperature for 130 minutes for the first aging. The reaction mixture was quenched to 100 ° C. or lower, transferred to a precipitation tank equipped with a stirrer, and water was added to the tank. The produced cellulose acetate was precipitated, centrifuged to remove the solvent, transferred to a water washing tank, thoroughly washed with water in this tank, taken out of the tank and dried.
The obtained cellulose diacetate had a total acetyl group substitution degree of 2.19, a 2-position acetyl group substitution degree of 0.76, a 3-position acetyl group substitution degree of 0.79, and a 6-position acetyl group substitution degree of 0. .64.

Example 1 (acylation of cellulose diacetate with acetic anhydride and benzoyl chloride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 500 mL three-necked flask) 0.79, 6-position Ac group: 0.64) 13.0 g (glucopyranose unit 0.051 mol), pyridine 117.0 g (1.50 mol) and acetic anhydride 0.91 g (0.009 mol) were added, The liquid temperature was adjusted to 50 ° C. and dissolved. When the moisture in the system was measured using a Karl Fischer moisture meter, the moisture in the system was 365 ppm. Subsequently, 13.1 g (0.09 mol) of benzoyl chloride was added dropwise over 30 minutes, the liquid temperature was adjusted to 30 ° C., and the mixture was aged for 12 hours while maintaining the temperature. After aging, 259.3 g of methanol was added to the reaction solution to treat the remaining benzoyl chloride. Subsequently, after raising the liquid temperature to 60 ° C. and keeping the liquid uniform, the liquid temperature is cooled to 10 ° C. at a rate of 10 ° C./1 hour, and further stirred at 10 ° C. for 1 hour, Crystallization was performed, and the precipitated granular material was filtered and rinse-washed with 57.6 g of methanol. The obtained granular material was put into 288.1 g of methanol, heated to 55 ° C., heated and stirred to extract impurities in the filtered material, filtered, and the obtained granular material was mixed with 28.8 g of methanol. After rinsing and rinsing, drying under reduced pressure overnight yielded 14.6 g (yield: 90.1%) of cellulose acetate benzoate. The degree of substitution and substituent distribution of this product were measured by ¹³ C-NMR. The 2-position Ac group: 0.86, the 3-position Ac group :, 0.82, the 6-position Ac group: 0.86, and the 2-position Bz Group: 0.14, 3-position Bz group: 0.21, 6-position Bz group: 0.10. The coloring degree was 150 in terms of Hazen unit color.

Example 2 (Acylation of cellulose diacetate with acetic anhydride and benzoyl chloride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask) 0.79, 6-position Ac group: 0.64) 50.0 g (glucopyranose unit 0.20 mol) and pyridine 450.3 g (5.7 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 581.5 ppm. After adjusting the liquid temperature to 50 ° C. and adding 2.5 g (0.03 mol) of acetic anhydride, the liquid temperature was raised to 60 ° C. and aging was performed for 1 hour. Subsequently, the liquid temperature was lowered to 50 ° C., 40.5 g (0.29 mol) of benzoyl chloride was added dropwise over 30 minutes, the liquid temperature was adjusted to 60 ° C., and the mixture was aged for 7 hours while maintaining the temperature. After aging, the liquid temperature was lowered to 40 ° C. or lower, 200.3 g of methanol was added, and the remaining benzoyl chloride was treated. Subsequently, the reaction solution was added to 2000.2 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 200.0 g of methanol, and redissolved with 801.1 g of acetone. The solution was put into 4005.6 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 400.6 g of methanol, and dried under reduced pressure overnight to obtain 57.0 g (yield: 89.7%) of cellulose acetate benzoate. The degree of substitution and substituent distribution of this product were measured by ¹³ C-NMR. The 2-position Ac group: 0.81, the 3-position Ac group: 0.82, the 6-position Ac group: 0.81, and the 2-position Bz group : 0.18, 3-position Bz group: 0.23, and 6-position Bz group: 0.15. The coloring degree was 150 in terms of Hazen unit color.

Example 3 (Acylation of cellulose diacetate with acetic acid and benzoyl chloride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask) 0.79, 6-position Ac group: 0.64) 50.1 g (glucopyranose unit 0.20 mol), pyridine 450.1 g (5.7 mol) and acetic acid 7.2 g (0.07 mol) were added, and 50 The liquid temperature was adjusted to 0 ° C. and dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 518.5 ppm. Subsequently, 35.1 g (0.25 mol) of benzoyl chloride was added dropwise over 30 minutes, the liquid temperature was adjusted to 60 ° C., and the mixture was aged for 7 hours while maintaining the temperature. After aging, the liquid temperature was lowered to 40 ° C. or lower, and 1000.3 g of methanol was added to the reaction liquid to treat the remaining benzoyl chloride. Subsequently, after raising the liquid temperature to 60 ° C. and keeping the liquid uniform, the liquid temperature is cooled to 10 ° C. at a rate of 10 ° C./1 hour, and further stirred at 10 ° C. for 1 hour, Crystallization was performed, and the precipitated particulate matter was filtered and rinse-washed with 100.4 g of methanol. The obtained granular material was put into 1000.5 g of methanol, heated to 50 ° C., heated and stirred to extract impurities in the filtered material, filtered, and the obtained granular material was mixed with 100.9 g of methanol. After rinsing and rinsing, the residue was dried overnight under reduced pressure to obtain 55.6 g (yield: 90.3%) of cellulose acetate benzoate. The degree of substitution and substituent distribution of this product were measured by ¹³ C-NMR. The 2-position Ac group: 0.86, the 3-position Ac group :, 0.82, the 6-position Ac group: 0.86, and the 2-position Bz Group: 0.15, 3-position Bz group: 0.21, 6-position Bz group: 0.10. The degree of coloring was 400 in terms of Hazen unit colors.

Example 4 (Acylation of cellulose diacetate using acetic anhydride and benzoyl chloride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask) 0.79, 6-position Ac group: 0.64) 50.1 g (glucopyranose unit 0.20 mol) and pyridine 450.1 g (5.7 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 401.8 ppm. After adjusting the liquid temperature to 50 ° C. and adding 3.6 g (0.04 mol) of acetic anhydride, the liquid temperature was raised to 60 ° C. and aging was performed for 7 hours. Subsequently, the liquid temperature was lowered to 50 ° C., and 38.0 g (0.27 mol) of benzoyl chloride was added dropwise over 30 minutes, and then the liquid temperature was adjusted to 60 ° C. and the mixture was aged for 7 hours while maintaining the temperature. After aging, the liquid temperature was lowered to 40 ° C. or lower, and 8.7 g of methanol was added to treat the remaining benzoyl chloride. Subsequently, the reaction solution was added to 1999. 4 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 199.9 g of methanol, and redissolved with 800.2 g of acetone. The solution was poured into 4000.7 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 400.1 g of methanol, and dried under reduced pressure overnight to obtain 56.2 g (yield: 91.2%) of cellulose acetate benzoate. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, the 2-position Ac group: 0.87, the 3-position Ac group: 0.80, the 6-position Ac group: 0.89, and the 2-position Bz group : 0.15, 3-position Bz group: 0.21, 6-position Bz group: 0.09. The coloring degree was 150 in terms of Hazen unit color.

Example 5 (Acylation of cellulose diacetate with acetyl chloride and benzoyl chloride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask) 0.79, 6-position Ac group: 0.64) 30.0 g (glucopyranose unit 0.12 mol) and pyridine 269.9 g (3.4 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 624.2 ppm. After adjusting the liquid temperature to 50 ° C. and adding 3.3 g (0.04 mol) of acetyl chloride, the liquid temperature was raised to 60 ° C. and aging was performed for 7 hours. Subsequently, the liquid temperature was dropped to 50 ° C., and 17.9 g (0.13 mol) of benzoyl chloride was added dropwise over 30 minutes, the liquid temperature was adjusted to 60 ° C., and the mixture was aged for 7 hours while maintaining the temperature. After aging, the solution temperature was lowered to 40 ° C. or lower, and 4.1 g of methanol was added to treat the remaining benzoyl chloride. Subsequently, the reaction solution was added to 1199.8 g of methanol for reprecipitation. The obtained fibrous solid was filtered, rinsed with 120.0 g of methanol, and redissolved with 480.3 g of acetone. The solution was poured into 2401.6 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 240.2 g of methanol, and then dried under reduced pressure overnight to obtain 33.2 g (yield: 89.7%) of cellulose acetate benzoate. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, 2-position Ac group: 0.79, 3-position Ac group: 0.83, 6-position Ac group: 0.84, 2-position Bz group : 0.17, 3-position Bz group: 0.22, 6-position Bz group: 0.15. The degree of coloring was 500 or more in terms of Hazen unit colors.

Example 6 (acylation of cellulose diacetate with acetic anhydride and benzoyl chloride)
Cellulose diacetate dried under reduced pressure overnight at 60 ° C. in a glass 1 L three-necked flask (total substitution degree of acetyl group: 1.81, 2-position Ac group: 0.62, 3-position Ac group: 0 .57, 6-position Ac group: 0.62) 10.0 g (glucopyranose unit 0.042 mol) and pyridine 90.0 g (1.1 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 1110.2 ppm. After adjusting the liquid temperature to 50 ° C. and adding 0.81 g (0.008 mol) of acetic anhydride, the liquid temperature was raised to 60 ° C. and aging was performed for 1 hour. Subsequently, the liquid temperature was lowered to 50 ° C., and 13.8 g (0.097 mol) of benzoyl chloride was added dropwise over 30 minutes, the liquid temperature was adjusted to 30 ° C., and the mixture was aged for 12 hours while maintaining the temperature. After aging, the liquid temperature was lowered to 40 ° C. or less, and 40.0 g of methanol was added to treat the remaining benzoyl chloride. Subsequently, the reaction solution was added to 399.9 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 40.0 g of methanol, and then redissolved with 160.0 g of acetone. The solution was poured into 800.6 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 80.2 g of methanol, and dried under reduced pressure overnight to obtain 11.7 g (yield: 82.1%) of cellulose acetate benzoate. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, 2-position Ac group: 0.72, 3-position Ac group: 0.61, 6-position Ac group: 0.83, 2-position Bz group : 0.30, 3-position Bz group: 0.46, and 6-position Bz group: 0.09. The coloring degree was 50 in terms of Hazen unit colors.

Example 7 (Acylation of cellulose diacetate with propionic anhydride and benzoyl chloride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask) 0.79, 6-position Ac group: 0.64) 10.0 g (glucopyranose unit 0.039 mol) and pyridine 90.0 g (1.1 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 793.7 ppm. After adjusting the liquid temperature to 50 ° C. and adding 0.92 g (0.007 mol) of propionic anhydride, the liquid temperature was raised to 60 ° C. and aging was performed for 1 hour. Subsequently, the liquid temperature was dropped to 50 ° C., and 8.24 g (0.058 mol) of benzoyl chloride was added dropwise over 30 minutes, the liquid temperature was adjusted to 60 ° C., and the mixture was aged for 7 hours while maintaining the temperature. After aging, the liquid temperature was lowered to 40 ° C. or less, and 40.1 g of methanol was added to treat the remaining propionic anhydride. Subsequently, the reaction solution was added to 400.2 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 40.0 g of methanol, and then redissolved with 160.0 g of acetone. The solution was poured into 800.1 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 80.3 g of methanol, and dried under reduced pressure overnight to obtain 11.4 g of cellulose acetate benzoate propionate (yield: 89.9%). It was. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, 2-position Ac group: 0.77, 3-position Ac group: 0.77, 6-position Ac group: 0.66, 2-position Bz group : 0.14, 3-position Bz group: 0.21, 6-position Bz group: 0.13, 2-position Pr group: 0.09, 3-position Pr group: 0.13, 6-position Pr group: 0.11 there were. The degree of coloring was 250 in terms of Hazen unit colors.

Example 8 (Acylation of cellulose diacetate using acetic anhydride and propionic anhydride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask) 0.79, 6-position Ac group: 0.64) 10.0 g (glucopyranose unit 0.039 mol) and pyridine 90.0 g (1.1 mol) were dissolved. When the moisture in the system was measured using a Karl Fischer moisture meter, the moisture in the system was 806.87 ppm. After adjusting the liquid temperature to 50 ° C. and adding 0.73 g (0.007 mol) of acetic anhydride, the liquid temperature was raised to 60 ° C. and aging was performed for 1 hour. Subsequently, the liquid temperature was lowered to 50 ° C., and 7.62 g (0.058 mol) of propionic anhydride was added dropwise over 30 minutes, the liquid temperature was adjusted to 60 ° C., and the mixture was aged for 7 hours while maintaining the temperature. After aging, the liquid temperature was lowered to 40 ° C. or less, and 40.2 g of methanol was added to treat the remaining propionic anhydride. Subsequently, the reaction solution was added to 400.2 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 40.3 g of methanol, and then redissolved with 160.0 g of acetone. The solution was poured into 801.1 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 80.0 g of methanol, and dried under reduced pressure overnight to obtain 11.1 g (yield: 95.0%) of cellulose acetate propionate. . When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, the 2-position Ac group: 0.83, the 3-position Ac group: 0.80, the 6-position Ac group: 0.76, and the 2-position Pr group : 0.17, 3-position Pr group: 0.17, 6-position Pr group: 0.24. The coloring degree was 40 in terms of Hazen unit colors.

Comparative Example 1 (Acylation of cellulose diacetate with benzoyl chloride (total benzoate))
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask) 0.79, 6-position Ac group: 0.64) 50.0 g (glucopyranose unit 0.19 mol) and pyridine 450.3 g (5.7 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 581.5 ppm. The liquid temperature was adjusted to 30 ° C., and 35.9 g (0.26 mol) of benzoyl chloride was added, followed by aging at 30 ° C. for 12 hours. Subsequently, the reaction solution was poured into 2143.7 g of methanol to precipitate a fibrous solid. The obtained fibrous solid was collected by filtration, rinsed with 214.4 g of methanol, and redissolved with 800.1 g of acetone. The solution was poured into 4001.5 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 400.1 g of methanol, and dried under reduced pressure overnight to obtain 60.8 g (yield: 91.3%) of cellulose acetate benzoate. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, the 2-position Ac group: 0.76, the 3-position Ac group: 0.79, the 6-position Ac group: 0.64, and the 2-position Bz group : 0.24, 3-position Bz group: 0.21, 6-position Bz group: 0.36. The coloring degree was 60 in terms of Hazen unit colors.

Comparative Example 2 (Acylation of cellulose diacetate with benzoyl chloride (total benzoate))
Cellulose diacetate (2-position Ac group: 0.87, 3-position Ac group: 0.85, 6-position Ac group: 0.005 g) dried in a vacuum dryer at 60 ° C. overnight in a glass 1 L three-necked flask. 73) 13.0 g (glucopyranose unit 0.05 mol) and pyridine 117.0 g (1.48 mol) were dissolved. When the moisture in the system was measured using a Karl Fischer moisture meter, the moisture in the system was 264.0 ppm. The liquid temperature was adjusted to 30 ° C. and 6.1 g (0.04 mol) of benzoyl chloride was added, followed by aging at 30 ° C. for 12 hours. Subsequently, 245.0 g of methanol was added to the reaction liquid, and then the liquid temperature was raised to 60 ° C., and the liquid was kept uniform, and then cooled to 10 ° C. at a rate of 10 ° C./1 hour. Further, the mixture was further stirred at 10 ° C. for 1 hour for crystallization, and the precipitated granular material was filtered and rinsed with 54.4 g of methanol. The obtained granular material was put into 272.2 g of methanol, heated to 55 ° C., heated and stirred to extract impurities in the granular material, filtered, and the obtained granular material was converted to 27.2 g of methanol. After rinsing and rinsing, the residue was dried overnight under reduced pressure to obtain 13.5 g (yield: 85.0%) of cellulose acetate benzoate. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, 2-position Ac group: 0.87, 3-position Ac group: 0.86, 6-position Ac group: 0.72, 2-position Bz group : 0.13, 3-position Bz group: 0.20, and 6-position Bz group: 0.21. The degree of coloring was 100 in terms of Hazen unit colors.

Comparative Example 3 (Acylation of cellulose diacetate using acetic anhydride and benzoyl chloride; with isolation treatment)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask) 0.79, 6-position Ac group: 0.64) 50.1 g (glucopyranose unit 0.20 mol) and pyridine 450.1 g (5.7 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 401.8 ppm. After adjusting the liquid temperature to 50 ° C. and adding 7.3 g (0.08 mol) of acetic anhydride, the liquid temperature was raised to 60 ° C. and aging was performed for 7 hours. Subsequently, the reaction solution was put into 2000.1 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 199.9 g of methanol, and then dried under reduced pressure in a vacuum dryer at 60 ° C. overnight. The dried fibrous solid was redissolved with 450.1 g (5.7 mol) of pyridine, and 38.0 g (0.27 mol) of benzoyl chloride was added dropwise thereto at room temperature over 30 minutes, and the liquid temperature was adjusted to 60 ° C. The mixture was aged for 7 hours while maintaining the temperature. After aging, the liquid temperature was lowered to 40 ° C. or lower, and 8.7 g of methanol was added to treat the remaining benzoyl chloride. Subsequently, the reaction solution was added to 1999. 4 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 199.9 g of methanol, and redissolved with 800.2 g of acetone. The solution was poured into 4000.7 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 400.1 g of methanol, and dried under reduced pressure overnight to obtain 54.1 g (yield: 89.6%) of cellulose acetate benzoate. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, the 2-position Ac group: 0.87, the 3-position Ac group: 0.81, the 6-position Ac group: 0.87, and the 2-position Bz group : 0.14, 3-position Bz group: 0.21, 6-position Bz group: 0.09. The coloring degree was 350 in terms of Hazen unit colors. According to this method, although cellulose acetate benzoate having a desired substitution degree can be obtained, after the acetylation reaction in the former stage, the quench treatment is performed, the reaction product is isolated, and then the benzoylation reaction in the latter stage is performed. Therefore, it is industrially disadvantageous in that the number of steps is large and complicated operations are increased. In addition, considering the water contained in cellulose diacetate, it is necessary to accurately calculate the amount hydrolyzed by the water and set the amount of acetic anhydride used in the previous stage, which is also complicated .

Comparative Example 4 (acylation of cellulose diacetate using benzoyl chloride and acetic anhydride)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask: 0.79, 6-position Ac group: 0.64) 24.0 g (glucopyranose unit 0.09 mol) and pyridine (Py) 456.0 g (5.7 mol) were dissolved. This was azeotropically dehydrated, and 173.5 g of Py was distilled off. Thereafter, 129.2 g of Py was added to the system, and the water content in the system was measured using a Karl Fischer moisture meter. The water content in the system was 289 ppm. The liquid temperature was adjusted to 25 ° C., and 6.3 g (0.045 mol) of benzoyl chloride was added dropwise over 30 minutes, and then the liquid temperature was adjusted to 40 ° C. and aged for 5 hours while maintaining the temperature. Subsequently, 6.39 g (0.06 mol) of acetic anhydride was added, and then the liquid temperature was raised to 60 ° C. and aging was performed for 5 hours. Subsequently, after the liquid temperature was lowered to 40 ° C. or less, 200.1 g of methanol was added to treat the remaining acetic anhydride. Subsequently, the reaction solution was added to 1770.4 g of methanol for reprecipitation. The obtained fibrous solid was filtered, rinsed with 300.9 g of methanol, and redissolved with 348.2 g of acetone. The solution was put into 1770.7 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 150.1 g of methanol, and dried under reduced pressure overnight to obtain 24.7 g (yield: 88.4%) of cellulose acetate benzoate. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, 2-position Ac group: 0.91, 3-position Ac group: 0.96, 6-position Ac group: 0.69, 2-position Bz group : 0.09, 3-position Bz group: 0.04, 6-position Bz group: 0.31. The degree of coloring was 100 in terms of Hazen unit colors.

Comparative Example 5 (Acylation of cellulose diacetate using propionic anhydride and benzoyl chloride; with isolation treatment)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask: 0.79, 6-position Ac group: 0.64) 10.0 g (glucopyranose unit 0.039 mol) and pyridine 90.0 g (1.1 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 650.98 ppm. After adjusting the liquid temperature to 50 ° C. and adding 3.69 g (0.028 mol) of propionic anhydride, the liquid temperature was raised to 60 ° C. and aging was performed for 7 hours. Subsequently, the reaction solution was put into 400.1 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 40.3 g of methanol, and then dried under reduced pressure in a vacuum dryer at 60 ° C. overnight. The dried fibrous solid was redissolved with 90.1 g (1.1 mol) of pyridine, and 4.23 g (0.030 mol) of benzoyl chloride was added dropwise thereto at room temperature over 30 minutes, and the liquid temperature was adjusted to 60 ° C. The mixture was aged for 7 hours while maintaining the temperature. After aging, the liquid temperature was lowered to 40 ° C. or less, and 40.1 g of methanol was added to treat the remaining propionic anhydride. Subsequently, the reaction solution was added to 400.0 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 40.0 g of methanol, and then redissolved with 160.0 g of acetone. The solution was poured into 800.0 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 80.1 g of methanol, and then dried under reduced pressure overnight to obtain 11.9 g (yield: 93.8%) of cellulose acetate benzoate propionate. It was. When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, 2-position Ac group: 0.78, 3-position Ac group: 0.74, 6-position Ac group: 0.68, 2-position Bz group : 0.14, 3-position Bz group: 0.17, 6-position Bz group: 0.17, 2-position Pr group: 0.08, 3-position Pr group: 0.09, 6-position Pr group: 0.15 there were. The degree of coloring was 200 in terms of Hazen unit colors.

Comparative Example 6 (Acylation of cellulose diacetate using acetic anhydride and propionic anhydride; with isolation treatment)
Cellulose diacetate (cellulose diacetate obtained in Production Example 1; 2-position Ac group: 0.76, 3-position Ac group: vacuum-dried overnight at 60 ° C. in a glass 1 L three-necked flask: 0.79, 6-position Ac group: 0.64) 10.0 g (glucopyranose unit 0.039 mol) and pyridine 90.0 g (1.1 mol) were dissolved. When the water content in the system was measured using a Karl Fischer moisture meter, the water content in the system was 600.30 ppm. After adjusting the liquid temperature to 50 ° C. and adding 8.04 g (0.079 mol) of acetic anhydride, the liquid temperature was raised to 60 ° C. and aging was performed for 7 hours. Subsequently, the reaction solution was put into 400.1 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 40.3 g of methanol, and then dried under reduced pressure in a vacuum dryer at 60 ° C. overnight. The dried fibrous solid was redissolved with 90.1 g (1.1 mol) of pyridine, and 4.61 g (0.035 mol) of propionic anhydride was added dropwise to the mixture at room temperature over 30 minutes. The temperature was maintained and the mixture was aged for 7 hours. After aging, the liquid temperature was lowered to 40 ° C. or less, and 40.2 g of methanol was added to treat the remaining propionic anhydride. Subsequently, the reaction solution was added to 400.2 g of methanol to perform reprecipitation. The obtained fibrous solid was filtered, rinsed with 40.3 g of methanol, and then redissolved with 160.0 g of acetone. The solution was poured into 801.1 g of methanol to precipitate a fibrous solid again. The obtained fibrous solid was collected by filtration, rinsed with 80.0 g of methanol, and then dried under reduced pressure overnight to obtain 10.6 g (yield: 90.7%) of cellulose acetate propionate. . When the substitution degree and substituent distribution of this product were measured by ¹³ C-NMR, the 2-position Ac group: 0.82, the 3-position Ac group: 0.78, the 6-position Ac group: 0.76, and the 2-position Pr group : 0.18, 3-position Pr group: 0.22, and 6-position Pr group: 0.24. The coloring degree was 50 in terms of Hazen unit colors.

Evaluation test <Production of film>
15 parts by weight of the cellulose derivative (cellulose mixed acylate) obtained in Examples and Comparative Examples, 72 parts by weight of methylene chloride, and 13 parts by weight of methanol were placed in a sealed container, and the mixture was dissolved over 24 hours with slow stirring. The dope was filtered under pressure and then allowed to stand for 24 hours to remove bubbles in the dope.
The dope was cast on a glass plate at a dope temperature of 25 ° C. (room temperature) using a bar coater. The cast glass plate was sealed and allowed to stand for 2 minutes in order to make the surface uniform (leveling). After leveling, the film was peeled off from the glass plate after drying for 8 minutes with a warm air dryer at 40 ° C. The film was then supported on a stainless steel frame and dried for 20 minutes with a hot air dryer at 100 ° C. to obtain a film (unstretched film).
In addition, this film (unstretched film) was tan δ using a tensile tester (Orientec Co., Ltd., “UCT-5T”) and an environmental unit (Orientec Co., Ltd., “TLF-U3”). The film was stretched 1.3 times at a rate of 250% / min in the width direction at a temperature at which the film became a peak top.
The dynamic viscoelasticity in the width direction of this unstretched film was measured. Table 1 shows the peak top of tan δ and the storage elastic modulus at that time together with the film thicknesses of the unstretched film and the stretched film. Table 1 also shows the content of sulfate radicals in the cellulose derivatives obtained in Examples and Comparative Examples.

<Measurement of optical characteristics (retardation value, photoelastic coefficient)>
Three-dimensional refractive index measurement of the above-obtained film (film before stretching, film after stretching) at a wavelength of 590 nm using an elliptical polarization measuring device (“KOBRA-WPR” manufactured by Oji Scientific Instruments) The refractive index nx in the slow axis direction, the refractive index ny in the fast axis direction, and the refractive index nz in the thickness direction are obtained, and from these values, the in-plane retardation value Re and the thickness direction of the film are obtained. The retardation value Rth was calculated based on the formula defined by the following formula. The in-plane retardation value Re is a value near the center of the film.
Re = | nx−ny | × d
Rth = {(nx + ny) / 2−nz} × d
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the film thickness direction, and d is the film thickness)
The photoelastic coefficient is obtained by applying a load to the film before stretching, measuring an in-plane retardation value Re of the film, and dividing this value Re by the film thickness d to obtain Δn = Re / d. Then, Re is measured while changing the applied load, and Δn is calculated. From the obtained data, a load vs. Δn curve was created, and the slope was taken as the photoelastic coefficient. The KOBRA-WPR was used for the measurement of retardation. The results are shown in Table 1. The values of Re and Rth in the table are values in terms of film thickness of 80 μm (values when d = 80 μm).

  The total degree of benzoyl group substitution of the cellulose acetate benzoate obtained in Example 1 is 0.45, and the total degree of benzoyl group substitution of the cellulose acetate benzoate obtained in Comparative Example 2 is 0.54. When a benzoyl group is introduced into the hydroxyl group of cellulose diacetate, the polarizability increases and the value of Rth also increases negatively. However, as in Example 1, the introduction position of the benzoyl group is controlled so that the 2nd position of the glucose skeleton, By selectively introducing into the 3-position (the aromatic ring is arranged in a direction perpendicular to the polymer chain), Rth can be increased negatively even if the amount of benzoyl group introduced is not so large. The effect of introducing a benzoyl substituent (an effect of increasing the Rth value negatively) appears remarkably after stretching.

1 is a diagram showing ¹³ C-NMR spectra (partial) of cellulose acetate benzoate obtained in Example 1, Example 2 and Comparative Example 1. FIG.

Claims (9)

  A cellulose mixed acylate having a total acyl group substitution degree of 2.7 to 3.0 by introducing a plurality of acyl groups having different reactivity into cellulose acetate having a total substitution degree of acetyl group of 1.5 to 2.9. And (i) a first carboxylic acid corresponding to an acyl group having a relatively high reactivity and a second carboxyl corresponding to an acyl group having a relatively low reactivity. A mixed acid anhydride with an acid and the acid anhydride or acid halide derivative of the second carboxylic acid, or (ii) a first carboxylic acid corresponding to an acyl group having a relatively high reactivity; Reacting with an acid halide derivative of a second carboxylic acid corresponding to an acyl group having a relatively low reactivity, or (iii) of the first carboxylic acid corresponding to an acyl group having a relatively high reactivity. Acid anhydride or acid halide induction After reacting the body, the acid anhydride or acid halide derivative of the second carboxylic acid corresponding to the acyl group having a relatively low reactivity is reacted without quenching or isolating the reaction product. A method for producing a cellulose mixed acylate, wherein the acyl group having a relatively high reactivity is preferentially introduced into the 6-position of the glucose skeleton.   The method for producing a cellulose mixed acylate according to claim 1, wherein the first carboxylic acid is a saturated aliphatic carboxylic acid and the second carboxylic acid is an aromatic carboxylic acid.   The method for producing a cellulose mixed acylate according to claim 1 or 2, wherein the first carboxylic acid is a saturated aliphatic carboxylic acid having 2 to 4 carbon atoms.   In (i), 0.95 to 1.2 mol of the mixed acid anhydride of the first carboxylic acid and the second carboxylic acid is added to the raw material cellulose acetate with respect to 1 mol of the hydroxyl group at the 6-position of the raw material cellulose acetate. The method for producing a cellulose mixed acylate according to claim 1, wherein the acid anhydride or acid halide derivative of the second carboxylic acid is reacted.   In (ii), 0.95 to 1.2 mol of the first carboxylic acid is added to the raw material cellulose acetate with respect to 1 mol of the hydroxyl group at the 6-position of the raw material cellulose acetate, and the acid halide derivative of the second carboxylic acid The method for producing a cellulose mixed acylate according to claim 1, wherein:   In the former stage of (iii), 0.48 to 0.6 mol of an acid anhydride derivative of the first carboxylic acid is added to the raw material cellulose acetate and reacted with respect to 1 mol of the hydroxyl group at the 6-position of the raw material cellulose acetate. Or 0.95 to 1.2 mol of the acid halide derivative of the first carboxylic acid with respect to 1 mol of the hydroxyl group at the 6-position of the raw material cellulose acetate, followed by quenching treatment or reaction product The method for producing a cellulose mixed acylate according to claim 1, wherein the acid anhydride or acid halide derivative of the second carboxylic acid is reacted in the subsequent stage without performing the isolation treatment.   The acyl group total substitution degree is 2.7 to 3.0, the acetyl group total substitution degree is 1.5 to 2.9, and the acyl group having a lower reactivity than the acetyl group is 0.1 to 1.5. The sum of the degree of acyl group substitution that is less reactive than the acetyl group at the 2-position and the degree of acyl group substitution that is less reactive than the acetyl group at the 3-position is less reactive than the acetyl group at the 6-position. Greater than twice the degree of acyl group substitution (provided that if the acyl groups that are less reactive than the acetyl groups at the 2-, 3- and 6-positions are all aliphatic acyl groups, the acetyl group at the 2-position) The sum of the degree of acyl group substitution that is less reactive and the degree of acyl group substitution that is less reactive than the acetyl group at the 3-position is 1.3 times the degree of acyl group substitution that is less reactive than the acetyl group at the 6-position. Cellulose mixture characterized by Shireto.   The cellulose acylate according to claim 7, wherein the acyl group having a lower reactivity than the acetyl group is an aromatic acyl group.   The cellulose mixed acylate according to claim 7 or 8, wherein the sulfate group content is 200 ppm by weight or less based on the cellulose mixed acylate.

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